I never heard that it was produced in the lungs, but who knows. All I read was that it is mainly produced in the pineal gland in the center of the brain. The ancient Egyptians knew about this as it was portrayed in their scriptures as the Eye of Horus.
The reason why many living things have this molecule is because it enables one to travel to different planes of existence. According to some, we exist in a physical plane of existence (aka physical matrix) that follows a certain set of laws. Other planes of existence have different sets of rules and parameters.
About the entities; many may be friendly, others not so much. Also, the misconceptions and misunderstandings between different entities may arise from the fact that entities that are used to being in one plane of existence adopt a certain mind frame due to the laws and constraints of their plane of existence, and it may be hard for them to comprehend another entity with a completely different mind/soul/energy frame that is used to residing in a different plane of existence or matrix.
This subject definitely warrants further study and research.
I think it was Descartes that said the pineal gland is what ties the ghost to the machine.
This is an interesting documentary based of Dr. Rick Strassmans work. It’s hosted by Joe Rogan and has some interesting information if you haven’t seen it.
https://m.youtube.com/watch?v=LtT6Xkk-kzk
The Egyptians probably knew about DMT. I have looked at a few paintings showing Acacia Trees which are one of nature’s richest sources of DMT.